Intermolecular interactions in ethanol solution of OABA: Raman, FTIR, DFT, M062X, MEP, NBO, FMO, AIM, NCI, RDG analysis

This study describes the effect of ethanol on the vibrational modes of ortho-aminobenzoic acid (OABA) using Raman and FTIR spectroscopy. The intermolecular interactions between OABA and ethanol mole-cules were analysed using DFT, IEFPCM, and M062X methods based on the B3LYP/6-311++G(d,p) basis set. The effect of the solvent at different concentrations on the C = O stretching vibration of OABA was studied. The most stable complex formed by OABA and the ethanol molecules was determined. OABA, ethanol, and OABA + ethanol complexes' Raman and IR spectra were simulated. The scaled theoretical and experimental results show good agreement with each other. Mulliken atomic charge distribution and NBO analysis were used to study the mechanism of intermolecular and intramolecular charge trans-fer. MEP, HUMO-LUMO gap, and other electronic properties are reported. Interactions at the critical points of connections were studied using topological (AIM, NCI, RDG, ELF, and LOL) analyses. The inter-action of OABA with ethanol molecules was determined by the carboxyl group of OABA and the hydroxyl group of ethanol.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the impact of ethanol on the vibrational modes of ortho-aminobenzoic acid (OABA) through Raman and FTIR spectroscopy. Molecular interactions between OABA and ethanol molecules are analyzed using various methods based on the B3LYP/6-311++G(d,p) basis set. The study focuses on the solvent’s effect on the C=O stretching vibration of OABA at different concentrations. The formation of the most stable OABA-ethanol complex is determined, and its Raman and IR spectra are simulated. Theoretical and experimental results show good agreement, and the mechanism of intermolecular and intramolecular charge transfer is studied using Mulliken atomic charge distribution and NBO analysis. The interaction between OABA and ethanol is primarily attributed to the carboxyl group of OABA and the hydroxyl group of ethanol.